HR: 0800h
AN: A21D-0909    [Abstracts]
TI: Planned Improvements to the MOPITT CO Product
AU: * Deeter, M N
EM: mnd@ucar.edu
AF: National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307
AU: Gille, J
EM: gille@ucar.edu
AF: National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307
AU: Edwards, D
EM: edwards@ucar.edu
AF: National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307
AU: Ho, S
EM: spho@ucar.edu
AF: National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307
AU: Yudin, V
EM: vyudin@ucar.edu
AF: National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307
AU: Emmons, L
EM: emmons@ucar.edu
AF: National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307
AU: Ziskin, D
EM: ziskin@ucar.edu
AF: National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307
AB: The next operational version ('Version 4') of the algorithm used to retrieve CO profiles from observations made by the MOPITT ('Measurements of Pollution in the Troposphere') instrument is now being evaluated internally. The new algorithm will include numerous enhancements such as (1) variable a priori, (2) incorporation of all available thermal-channel radiances, (3) radiance bias correction and (4) updated surface emissivity a priori. The current MOPITT CO product ('Version 3') exploits a 'global' a priori profile derived from a large database of in-situ profiles. Use of this a priori profile in regions where the mean profile is substantially different than the global a priori profile leads to consistent retrieval biases. The new product, in contrast, will be based on a variable a priori which describes consistent geographical and seasonal variations in CO mixing ratio. Current efforts for deriving the variable a priori emphasize the use of assimilation to exploit both MOPITT observations and chemical transport modeling. Because of significant biases observed in some of the MOPITT thermal-channel radiances, only a subset of the available thermal-channel radiances are used to retrieve the CO profile in Version 3. This obstacle will be overcome in Version 4 processing through the application of radiance bias correction. This feature will allow use of all available thermal-channel radiances and substantially increase the information content (as quantified by the Degrees of Freedom for Signal, for example) in some situations. In addition to a priori information relative to the CO profile, the MOPITT retrieval algorithm requires a priori values for surface temperature and surface emissivity. In Version 4, a priori surface emissivity values will exploit emissivity maps derived from collocated observations of MOPITT and MODIS. Compared to Version 3, the new emissivity values typically exhibit smaller uncertainties which will also increase the information content of the CO product.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
DE: 0394 Instruments and techniques
DE: 1640 Remote sensing (1855)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005